1. Field of the Invention
The present invention relates to a control device for controlling a drive source for running a vehicle, and more particularly, to a technique of discriminating anomaly of output control for such a running drive source.
2. Description of the Related Art
In recent years, drive-by-wire systems have come to be employed in vehicles mounted with an internal combustion engine (engine) or motor as a running drive source. In such a drive-by-wire system, a target torque (target output) is calculated in accordance with information on the operation of an accelerator pedal or the like, a target throttle opening for attaining the target torque is calculated, an actual throttle opening with which torque is being actually generated is detected using a throttle position sensor, and the throttle is controlled so that the actual torque may become equal to the target torque.
There have also been proposed anomaly discrimination techniques for the control devices of drive-by-wire systems. In the control device disclosed in Japanese Unexamined Patent Publication No. 2009-127549, for example, a difference between a target throttle valve opening calculated from a target torque and an actual throttle valve opening is obtained, and if the throttle opening difference is greater than a discrimination threshold value set on the basis of the target throttle opening and the engine rotating speed, it is judged that anomaly has occurred.
The engine rotating speed and the engine output torque vary and are not always the same. Thus, in cases where it is judged that anomaly has occurred when the difference (throttle opening difference) between the value related to the target torque and the value related to the actual torque is greater than the threshold value as in the above patent publication, the discrimination threshold value needs to be set to a large value in order to restrain erroneous anomaly discrimination.
If the threshold value for anomaly discrimination is set to a large value, however, accuracy of the anomaly discrimination lowers. Safety in case of anomaly is low especially when the engine is operating in a high-output condition as during acceleration of the vehicle, compared with the case where the engine is operating in a low-output condition, and therefore, it is desirable that anomaly discrimination should be made quickly and reliably.